The present invention is generally related to the field of audio output devices and, more particularly, is related to a system and method for sensing an audio output.
Since the early days of the record player, audio electronics has seen vast technological advancement. More recently, with the proliferation of computer technology, audio electronics has become integrated with the operation of a computer. Also, recent computer gaming software includes special sound effects that are generated in response to user input based upon information seen on a display device. Other computer software employs synthesized sound and other sound outputs and currently computers are available that can play compact disks on attached speakers, etc.
The technology employed to generate the sound has undergone a significant evolution as well. Early technology included the first stereo speaker systems that are driven by analog signals. Modern technology includes improved speaker systems and other audio equipment that are driven by analog sound signals as well as speaker systems that are driven by digital sound signals. Digitally driven systems may include multiple speaker systems that provide modem theater quality to in home sound systems. One digital interface that is commonly employed is the Sony/Phillips Digital Interface (S/PDIF) that can drive up to six different audio channels. Such sound systems may be employed in conjunction with home theater entertainment systems to watch television or movies.
Currently, computer systems may be outfitted with analog sound systems or digital sound systems to provide options for sound output in view of available audio technology to enhance the experience of the user. Unfortunately, the same computer systems may be outfitted with a number of other input/output devices such as display devices, keyboards, modems, a mouse, antenna, video cable input, printers, scanners, personal appliances, and many other devices. The proliferation of the available input/output devices generally results in a significant requirement on a computer to provide the number of input/output ports to service these various input/output devices. This can present a problem in that the corresponding physical size of a computer system becomes undesirably large.
Unfortunately, a computer system that provides both analog and digital sound output capability must include both a digital audio output port and an analog audio output port, thereby further exacerbating this problem. It may be possible to provide both analog and digital audio signals through a common audio output port. However, in such a case another problem is presented in that the computer system is not aware of whether an analog or digital signal is to be generated and transmitted through such a common audio output port.
In view of the foregoing, the present invention provides for a system and a method that are employed to detect whether an analog or digital sound system is coupled to a common audio output port provided in a computer system, stereo system, or other sound playback device. The analog sound system may be a powered stereo speaker system or other similar audio sound system. The digital sound system may include, for example, a Sony/Phillips Digital Interface (S/PDIF) receiver or other digital receiver.
According to one aspect of the present invention, a sound card or other such device is provided that includes an analog audio output system and a digital audio output system. Both the analog and digital audio output systems are coupled to a common audio output port through which either an analog or digital sound system is driven. The common audio output port provides a first line out and a second line out that may be employed to transmit the right and left channels of a stereo analog audio signal. The common audio output port also provides a common ground conductor. In this regard, the common audio output port may employ, for example, a xe2x85x9th inch mini-stereo connector or its equivalent. Only one of the analog and digital output systems are enabled to transmit sound through the common audio output port to the respective sound system at a time. Consequently, according to one aspect of the present invention, a system and method are provided to determine whether an analog or digital sound system is coupled to the common audio output port. This determination may be performed during a reset or startup phase of the operation of the computer system or stereo system, etc.
When an analog sound system is coupled to the common audio output port, the first and second line outs are both employed to relay left and right channels to the analog sound system. In contrast, when a digital sound system is coupled to the common audio output port, only one of the first and second lines out is employed to transmit a single digital signal. The remaining line out is coupled to ground.
According to the present invention, an audio output sensing system and method are employed to detect whether an analog sound system or a digital sound system is coupled to the common audio output port. In the present system, a predetermined sensing voltage is applied to the second line out. The second line out is then examined to determine the resulting voltage potential. Assuming that a connected digital sound system couples the second line out to ground, then the resulting voltage potential equals the ground potential. On the other hand, if an analog sound system is coupled to the second line out, the voltage potential on the second line out is much higher, given that the second line out is not grounded.
Thus, according to the audio output sensing system, a predetermined threshold is set somewhere between the ground potential and the highest voltage potential achieved when the sensing voltage is applied to the second line out. When the sensing voltage is applied to the second line out, if the resulting voltage potential is greater than the predetermined threshold, then the analog audio output system is enabled and the digital audio output system is disabled. On the other hand, if the resulting voltage potential is less than the predetermined threshold, then the digital audio output system is enabled and the analog audio output system is disabled. The audio output sensing system may be implemented in terms of software and general purpose hardware, dedicated hardware, or a combination of software/general purpose hardware and dedicated hardware.
The present invention may also be viewed as a method for sensing a sound system. In this regard, the method includes the steps of providing an audio output port having a first line out and a second line out, detecting an existence of a coupling between the second line out and a ground conductor, and, enabling one of an analog audio output system and a digital audio output systems based upon the existence of the coupling between the second line out and the ground conductor. The step of detecting an existence of a coupling between the second line out and a ground conductor further comprises the steps of applying a sensing voltage to the second line out, and, determining whether a voltage potential of the second line out is greater than a predetermined voltage threshold upon the application of the sensing voltage to the second line out.
Other features and advantages of the present invention will become apparent to a person with ordinary skill in the art in view of the following drawings and detailed description. It is intended that all such additional features and advantages be included herein within the scope of the present invention.